Rotary disc gate valve is a type of valve that combines the basic structure of a gate valve with a rotary operation. It drives the gate to open and close by rotating the valve stem. Its core feature is that the lifting and lowering of the valve disc (gate) is indirectly controlled by the rotary motion, which is different from the vertical lifting rod design of the traditional gate valve.
1. Structural design and working principle
Transmission mechanism
It adopts a concealed stem structure (rotary stem gate valve). The valve stem thread is engaged with the gate thread. When the valve stem rotates, it drives the gate to move vertically. Only the valve stem rotates without lifting.
The typical rotation angle is 90° (some models support multi-turn rotation). The torque is amplified by the worm gear transmission, and the operating torque is reduced by 40%-60%.
Sealing component
The gate is a parallel double-disc design. Bidirectional sealing is achieved by means of medium pressure or spring compensation. The sealing surface hardness is above HRC55 and the pressure resistance can reach PN40.
The valve seat adopts an elastic metal sealing ring combined with a polytetrafluoroethylene (PTFE) coating. The friction coefficient is as low as 0.05, which reduces the wear during opening and closing.
2. Performance advantages and limitations
Advantages
Small space occupation: The concealed rod design saves installation height and is suitable for pipeline systems with limited space (such as underground pipe networks); Strong anti-pollution: The full-diameter structure reduces the residual medium and is suitable for medium such as sewage and crude oil containing particulate matter; Long sealing life: The metal hard seal design can withstand temperatures up to 425°C and has a cycle opening and closing life of more than 100,000 times.
Limitations
Lack of adjustment function: It only supports full opening/full closing and cannot be used for flow regulation. Frequent partial opening can easily cause wear on the sealing surface; High maintenance complexity: The valve stem thread may become stuck due to lubrication failure after long-term operation, and special grease needs to be injected regularly.
3. Applications
| Field | Specific application scenarios | Technical adaptability |
|---|---|---|
| Municipal Engineering | Cut off the water inlet and drainage main pipe of the sewage treatment plant | Resistant to sewage impurities, concealed rod structure adapts to underground humid environment |
| Energy delivery | Crude oil pipeline pig launching device valve | The full-bore design allows the pig to pass through, and the bore matching accuracy is ±0.5mm |
4. Differences from conventional gate valves
| Comparison Items | Rotary Disc Gate Valve | Traditional rising stem gate valve |
|---|---|---|
| Operation method | Rotating the valve stem drives the gate to rise and fall | Direct vertical lift of valve stem |
| Sealing surface maintenance | The valve cover needs to be removed for | Quick access through packing gland |
| Applicable scenarios | Compact space, high frequency opening and closing environment | Where the valve position needs to be visually observed |
The valve has demonstrated high reliability and environmental adaptability in scenarios such as emergency shut-off of petrochemical pipelines and water system interception.
